Salmon carotenoids

However, when the carotenoids and acylglycerols were recombined, the salmon aroma developed. Combinations of alternate sources of fish acylglycerols along with crayfish carotenoids revealed that the necessary component for salmon flavor development was the presence of carotenoids specifically derived from salmon oil (Table III). Such results strongly suggest that the compound Is derived by co-oxldatlon of fish acylglycerols with salmon carotenoids, and that the precursor Is located In the carotenoid fraction. 

Animals that do not readily accept pelleted feeds may be enticed to do so if the feed carries an odor that induces ingestion. Color development is an important consideration in aquarium species and some animals produced for human food. External coloration is desired in aquarium species. Pink flesh in cultured salmon is desired by much of the consuming pubHc. Coloration, whether external or of the flesh, can be achieved by incorporating ingredients that contain pigments or by adding extracts or synthetic compounds. One class of additives that imparts color is the carotenoids. 

Other applications — P-carotene is used in various pet foods as both a colorant and a precursor to vitamin A. It can be applied to an array of animal foods designed for dogs, cats, fish, and birds. The antioxidant and precursory vitamin A properties increase the appeal and application of P-carotene in pet foods. Additionally, P-carotene is an important carotenoid that may assist in improving the color of birds, fish, and crustaceans. Dunaliella salina can serve as a source of algal feed for fish and crustaceans. The microalgae provide carotenoids that are essential for flesh coloring, particularly of salmon and crustaceans. 

Since animals cannot synthesize carotenoids, the pigments must be supplemented in the feeds of farmed species. Salmon and trout farming is now a huge business and feeding studies have shown that astaxanthin is very effective as a flesh pigmenter ... 

The carotenoid biosynthetic pathway leads to products such as vitamin A and its precursors carotene, responsible for the color of carrots or salmon, and lycopene, the color agent in tomatoes (Figure 11.12). Pathway products are sought for a variety of applications in food, medicine, and materials. Genes in the pathway from different organisms were combined and heterologously expressed in E. coli, a non-... 

Yamamura, Y. and Muto, S. (1961). Change of vitamin A and carotenoids during the development of salmon eggs. Bulletin of the Tokai Regional Fisheries Research Laboratory 19,171-179. 

Beta-carotene as determined in fruits and vegetables is used as a measure of the provitamin A content of foods. The column chromatographic procedure, which determines this content, does not separate a-carotene, p-carotene, and cryptoxanthin. Provitamin A values of some foods are given in Table 6-3. Carotenoids are not synthesized by animals, but they may change ingested carotenoids into animal carotenoids—as in, for example, salmon, eggs, and crustaceans. Usually carotenoid content of foods does not exceed 0.1 percent on a dry weight basis. 

Additionally, key secondary oxidation products contribute distinctive aromas characteristic to certain fish species. In salmon, co-oxldatlon of polyunsaturated fatty acids of fish oils with salmon-specific carotenoid pigments leads to the formation of a characterizing cooked salmon flavor compound, and changes the ratio of carbonyl compounds formed compared to that for pure fish oil. 

The Interaction of the carotenoid and the fatty acid fractions on Cellte were both necessary for the odor development to occur. Studies designed to confirm an Interaction of the carotenoid and fatty acid fractions In the development of salmon flavors showed that when carotenoid fractions from salmon oils were separated from the acylglycerol fraction by column chromatography, neither yielded a salmon-llke aroma during oxidation (Table III). 

In addition to the directed oxidation process responsible for the characteristic salmon flavor compound, carotenoids also were observed to Influence oxidation of polyunsaturated fatty acids In salmon oil systems (39). Typically, lipid oxidation of oils high In n-3 fatty acids produce Isomeric 2,4-heptadlenals as the major... 

Table III. Carotenoid and fatty acid contributions to cooked salmon flavor ...

Noninvasive methods were also used to establish whether the absorption and deposition of astaxanthin are affected by feeding the fish with or without astaxanthin supplementation in all or alternated meals (Wathne et al., 1998). The redness a of the salmon fed with astaxanthin in alternating meals was higher than that for fish fed with a mixture of colored and uncolored meals. A variation in the lightness L was also observed. Wathne et al. (1998) found that the total carotenoid concentration in the flesh could be estimated using the value a. However, the equation cannot be applied for the determination of the carotenoid content in other studies because the value of the coefficients depended on the fish physiological state and on the fish taxon. 

Foss, P. 1984. Carotenoids in diets for salmons. I. Pigmentation of rainbow trout with the individual optical isomers of astaxanthin in comparison with canthaxanthin. Aquaculture 41, 213-226. 

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